Humidity and temperature control system



Dec. 28, 1937. D. H. HILL 2,103,904

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Patented Dec. 28, 1937 PATENT OFFICE HUMIDITY AND TEMPERATURE coN'moL SYSTEM Dewey H. Hill, Macomb, Ill., assignor to Globe American Corporation, Kokomo, Ind., a corporation Application February 5, 1937, Serial No. 124,187 v 3 Claims.

This invention relates to a humidity and temperature control system particularly adaptable and designed for use in connection with mammoth incubators wherein it is desired to maintain a substantially constant and predetermined temperature and relative humidity, although the invention may have other applications.

The object of the invention is to automatically and without manual attention maintain a constant and relative humidity through the medium of a simple and cheaply constructed installation which willmost effectively and efliciently utilize the electric current in heating and eliminate extra humidifying mechanisms, fans, motors and 16 the like.

One feature of the invention resides in applying heat to the water to increase the relative humidity while utilizing such heat for temperature requirements along with a dry heating element, both the humidifying heater and the dry heater being controlled by the same circuit and temperature control device. Thus there is no waste of current or power in creating humidity in addition to creating heat.

The full nature of the invention will be readily Y understood from the accompanying drawing and the following description and claims:

Fig. 1 is a diagrammatic illustration of the method and system employed. Fig. 2 is a section 30 through the wet bulb of the humidity control.

In the drawing, there is shown a water pan I0 in which there is a constant level of water maintained through any suitable medium, such as a float controlled valve, not shown herein, the

35 water being introduced through the water inlet I I.

Below and immediately adjacent the underside of the bottom of the pan there is provided a heating element I2 of any suitable character which is electrically energized by the lead lines I3 and I4.

40 Surrounding the pan I0 and enclosing the heating element there is provided an insulating wall I5 for causing the major portion of the heat generated by the element I2 to be absorbed by the metal pan I0 and the water therein. Said pan 45 operates as a steam vapor generator, practically all of the heat from element. I2 being first absorbed by the water through the pan, the water givin ff steam vapor, raising the relative humidity within the compartment in which it is 50 placed. The sensible heat from the vapor is in therefrom in a suitable location of the compartment, there is a dry heating element I6 of any suitable and efllcient design. The lead line I3 is connected to one terminal of the heating element I6 as well as the heating element I2 and leads through the line I3a to one terminal of the source of current supply IT. The line I4 connects the other terminals of the heating elements I2 and I6 through the single pole, double throw switch Ma and the line Ilb. The switch Ila is of the snap action type having no neutral position when at rest. The pole of said switch Ila is connected to the other terminal of the source of current II through the single pole, single throw switch c.

Thus, for either heating element to be enerzed the switch Ilc must be closed and the switch a determines which of the two elements will be energized at a given time.

The switch Ilc is controlled by a dry temperature thermostat I8 of any suitable design, that indicated herein being of the wafer type having a temperature setting screw I9 associated therewith. Thus, upon an increase of dry temperature, the wafers of the thermostat I8 will be expanded to open the switch I30 and break the circult to both heating elements. Upon the temperature being lowered to or below a predetermined dry temperature, the wafers will contract to permit closing of the switch and energizing one or the other of said heating elements.

The humidity control is of the usual type and is indicated at 20. As illustrated herein, the control may be of that character embodying a series of wafers connected with a tube 2| (Fig. 2) surrounded by a fabric blanket 22 extending into the water supply contained in a vessel 23, the. tube and wafers being filled with volatile liquid affected as to its expansion and contraction by the cooling due to evaporation of moisture from the blanket.

In operation, heat will be supplied to the compartment from either of the heating elements I2 and I6. When the element I2 is energized, the water in the pan ID will be heated so that warm vapor will rise to increase the relative humidity and the temperature. By means of dry temperature thermostat I8 and the setting thereof, a predetermined dry temperature will thus be maintained through the medium of both of said elements. If the relative humidity falls below the setting of the wet bulb thermostat 20, the switch Ila will contact with the line I4 leading to the humidifying heating element I2, breaking the circuit through the line Ilb to the dry heating element l6. Heat and moisture will thus be generated from the pan ID. If the heat passes the predetermined temperature set in accordance with the dry temperaturethermostat N3, the switch I 40 will he opened so as to discontinue any heating effect by either heating element. If the relative humidity rises above the prescribed amount but the dry temperature requires raising, the switch I 40 will be closed and the wet bulb thermostat 20 will move switch a to close the circuit through line Ill: to the dry heating element It.

Thus, it will be apparent that all current consumed will be eflfective to build up and maintain both the temperature and humidity within the compartment without the use of outside or motor driven mechanisms.

The invention claimed is:

1. In a humidity and temperature control system for incubators, a water evaporating pan having an electric heating element therefor, a dry heating element, an electric circuit including a source of current common to said elements, a dry temperature thermostat for controlling said electric circuit and a humidity control thermostat for simultaneously making said circuit with one element and breaking it with the other.

2. In a humidity and temperature control system for incubators, a vapor producing electric heating element, a dry heat producing electric making and breaking said circuit, and a humidity control thermostat for simultaneously making 7 said circuit with one element and breaking it with the other.

3. In a humidity and temperature control system for incubators, a vapor producing electric heating element, a dry heat producing electric heating element spaced therefrom, an electric circuit including a source of current common to said elements, a dry temperature thermostat for breaking the circuit to both elements when the dry temperature rises above a predetermined amount and closing the circuit upon falling below said predetermined amount, and a humidity control thermostat in said circuit for simultaneously breaking the circuit to the dry temperature element and making it with the vaporizing element upon the relative humidity falling below a predetermined amount and simultaneously breaking the circuit to the vaporizing element and making it with the dry temperature element upon the relative humidity rising above said predetermined amount.

.DEWEY H. 

